您还可以使用捕获组(?P<user>模式)并像字典匹配['user']一样访问组。

string = '''someline abc\n
            someother line\n
            name my_user_name is valid\n
            some more lines\n'''

pattern = r'name (?P<user>.*) is valid'
matches = re.search(pattern, str(string), re.DOTALL)
print(matches['user'])

# my_user_name

你可以使用这样的代码:

import re
s = #that big string
# the parenthesis create a group with what was matched
# and '\w' matches only alphanumeric charactes
p = re.compile("name +(\w+) +is valid", re.flags)
# use search(), so the match doesn't have to happen 
# at the beginning of "big string"
m = p.search(s)
# search() returns a Match object with information about what was matched
if m:
    name = m.group(1)
else:
    raise Exception('name not found')

您需要一个捕获组。

p = re.compile("name (.*) is valid", re.flags) # parentheses for capture groups
print p.match(s).groups() # This gives you a tuple of your matches.

您可以使用组(用'('和')'表示)来捕获字符串的部分内容。匹配对象的group()方法会给出组的内容:

>>> import re
>>> s = 'name my_user_name is valid'
>>> match = re.search('name (.*) is valid', s)
>>> match.group(0)  # the entire match
'name my_user_name is valid'
>>> match.group(1)  # the first parenthesized subgroup
'my_user_name'

在Python 3.6+中，你也可以索引到匹配对象中，而不是使用group():

>>> match[0]  # the entire match 
'name my_user_name is valid'
>>> match[1]  # the first parenthesized subgroup
'my_user_name'

您需要从正则表达式中捕获。搜索模式，如果找到，使用group(index)检索字符串。假设执行了有效的检查:

>>> p = re.compile("name (.*) is valid")
>>> result = p.search(s)
>>> result
<_sre.SRE_Match object at 0x10555e738>
>>> result.group(1)     # group(1) will return the 1st capture (stuff within the brackets).
                        # group(0) will returned the entire matched text.
'my_user_name'

你可以使用匹配组:

p = re.compile('name (.*) is valid')

e.g.

>>> import re
>>> p = re.compile('name (.*) is valid')
>>> s = """
... someline abc
... someother line
... name my_user_name is valid
... some more lines"""
>>> p.findall(s)
['my_user_name']

这里我使用re.findall而不是re.search来获取my_user_name的所有实例。使用re.search，你需要从匹配对象的组中获取数据:

>>> p.search(s)   #gives a match object or None if no match is found
<_sre.SRE_Match object at 0xf5c60>
>>> p.search(s).group() #entire string that matched
'name my_user_name is valid'
>>> p.search(s).group(1) #first group that match in the string that matched
'my_user_name'

正如评论中提到的，你可能想让你的正则表达式是非贪婪的:

p = re.compile('name (.*?) is valid')

只取'name '和下一个' is valid'之间的东西(而不是让你的正则表达式取你组中的其他' is valid'。